Answer:
For question 2, it is C) 3a.
For question 3, it is B) 3.
Explanation:
For question 2, we are given that Mary's age is a and her mother's age is 3 times as old as Mary. The key word is "times" so this means that the expression can be written as 3a or 3 * a.
For question 3, the question asks for the greatest number that divides evenly into both 42 and 81. Using simple math, C and D automatically elliminates itself because one of the numbers divided gives a whole and the other gives a decimal. All is left is A and B. Obviously, a number divided by one will by itself so it stays even either way and the two numbers divided by 3 will give us two whole numbers and 3 is the greatest possible number so that concludes that it is B.